Power supply system



POWER SUPPLY SYSTEM Filed June 20, 1942 2 Sheets-Sheet l 1 wk 5 q i was 9 More? INVENTOR r v Geo/rm: Z. lssalwlz ATTORNEY G. L. USSELMAN POWER SUPPLY SYSTEM De'c. 31, 1946.

Filed June 20, 1942 2 Sheets-Sheet 2 [NSl/LA no;

INVENTOR 62-0194: 1. UssEMm/v.

Patented Dec. 31, 1946 George L. UsselmamPort Jeflerson, N. Y., assignor to Radio Corporation oi America, a corporation oi. Delaware 1 Application June '20. 1542, Serial No. 447,783

The present invention relates to an electric pump or charging means for supplying a high voltage direct current from a low voltage direct current from a low voltage direct current source.

The invention is especially suited for operating radio pulse generators of the type employed in radio locating apparatus, sometimes referred to as obstacle detection radio systems. In such apparatus, .it is required that the transmitter send .out periodically repeated radio wave pulses of extremely short duration. In order to produce radio wave pulses, it has been proposed to excite periodically the ultra short wave oscillator of the transmitter through a spark gap device which is in series with the oscillator and the charging voltage source and to which is supplied at periodic intervals a voltage of sufficient value to break down the gap. Reference is herein made to copending confidential applications of Clarence W. Hansel], Serial No. 427,266, filed January 19, 1942, and Nils E. Lindenbiad, Serial No. 441,311, filed May 1, 1942, for descriptions of the radio pulse generators to which the invention is particularly I applicable.

One of the objects 01 the present invention is to eliminate the use of a very high voltage direct voltage by means of apparatus which is simple and inexpensive to construct.

Briefly stated, the invention makes use of a continually variable capacitor for receiving a low voltage current charge and for converting or transforming this low voltage to a higher voltage current charge'which is stored on another capacitor until its value is high enough to discharge across a spark gap. -Rectifier circuits are empioyed for preventing the energy stored on both capacitors from returning to the originating point of supply. A line of predetermined constants in series with the spark gap may be used for assuring a definite time duration of discharge across the spark gap.

A short wave oscillator in series with the spark gap constitutes a load which produces ultra short wave energy solely during the time of discharge across the spark gap. Means are preferably em- 2 Claims. (01. 171-97) 2 played to prevent the discharge from being prolonged beyond the desired time interval, thus assuring the transmission of short and sharply defined pulses of energy from the oscillator without undesired trailing effects.

A more detailed description of the invention follows, in conjunction with the drawings wherein:

Figs. 1 and 2 illustrate the invention; and

Figs. 3, 4 and 5 illustrate details of condenser constructions which can be employed for the variable capacitor of Figs. 1 and 2.

The principles underlying the invention are extwo embodiments of plainable from the following well-known electrical relations:

ML I where Q is the amount of condenser charge,

C is the electrostatic capacity of the condenser,

E is the potential difference across the condenser,

and

where u is the constant of the dielectric in A is the area of the dielectric, and d is the thickness of the dielectric.

the condenser,

the distance between condenser plates).

Referring to Fig. 1 in more detail, there iS shown a low voltage direct current source of su ply A, indic-ated diagrammatically, for supplying a unidirectional high voltage to a loadR for satisfactory operation. Load R constitutes, in the radio pulse generator for which the invention is particularly designed, an ultra short wave oscillator such as a magnetron which requires a voltage on one of its electrodes (the anode, for example) to operate it satisfactorily. This oscillator R will oscillate only during the application or voltage pulses from the system, and because it functions momentarily it is possible to obtain a higher output than during a normal or continuous steady state. We thus apply a much higher voltage than normally applied to a magnetron electrode but I for a very short period of time, and take from the oscillatorR a short wave at high power which is then radiated by an antenna (not shown). In

series with the load B there is provided a sparkpacity of the condenser C1 is continuously varied by means of a motor M through a drive shaft 8. Condenser C1 is charged from direct current source A through the rectifier Ti, while the fixed condenser C is charged through the rectifier T2.

- As the motor M rotates, the capacitor Cl will vary between a small capacity condition and a large ly source A in order to prevent the voltage from .the source A from following through to prolong the spark or the-gap 61 when the latter gap,

breaks down. In Fig. 2, the line L replaces the condenser C of Fig. 1. This line is made upof sections of series inductance and shunt capacitance, of such constants that it provides a discharge of definite time duration across the gap In the operation of the system of Fig. 2,the condenser Ci serves to supply pulses or trickles 01' higher. voltage to the line .1. than the voltage applied .to the condenser from the direct ourcapacity condition. When the condenser C1 is 1 in the small capacity condition, its voltage will rise; but since the charge current applied thereto through the rectifier T1 cannot fiow backwards through the rectifier Til to the source A, it will of necessity fiow through the rectifier T: into the storing condenser C. When the condenser. C1 is varied to the large capacity. condition, the voltage thereon falls. Current cannot return from the condenser C to the condenser-Ci because oi the action of the rectifier To which acts as a check valve.

It will thus be seen that the condenser C1 obtains a low voltage charge from the direct cur rent supply A when its capacity is large and by virtue of its change in capacity to the small caacity condition produces an increase in the voltage on the condenser which is then transferred to the fixed condenser C where it is stored. As the value of the capacity of the condenser C1 is varied continuously by the motor M, the variable condenser will transfer increments of high voltage charge to the fixed condenser C until the latter reaches a value determined by the input voltage from source A and the variable capacity ratio of the variable condenser C1, and by the ultimate breakdown strength of the various'parts of the system. In general, the voltage developed on fixed condenser C will be the voltage of the di-' rect current source A multipliedby the ratio of maximum to minimum capacity of the condenser C1. When the condenser C is charged to apredetermined critical value, the spark gap G1 will break down and the condenser C will discharge across this gap, sending a surge of current through the load R (in this case a short wave radio transmitter) Fig. 2 is a modification of the system of Fig. I and operates generally upon the principle de scribed above. In Fig. 2 the capacity of the condenser C1 is varied by changing the dielectric constant a. The dielectric material between the plates of the condenser comprises a wheel I), which is preferably a serrated wheel composed of alternate sections of Titanium dioxide having a very high dielectric constant and air, or some other material of low dielectric constant. This wheel D is rotated between the electrode plates of condenser Ci-by means of shaft 8. in turn linked to the motor M. A second spark gap G2 is shown inserted in series between the two rectiflers T1, T2." Gap G2 is set Just above the sparking voltage of the direct current sup- P value determined byits constants.

rent source. Line L is then charged to a critical When this critical value is reached, the spark gap G1 breaks down and the line discharges across the spark gap G1 sending a surge of current through theload R. Rectifier T2 in Fig. 2 as in F18. 1 acts as a check valve and prevents the voltage on "line L from returning to thecondenser C1. In practice, in using a radio pulse generator or obstacle, detection system with the system of Fig.2, thegap G1 is synchronized by means not shown so that it sparks over during the time condenser .01

is being recharged. The spark gap G: serves to prevent trailing effects which might be caused in conventional systems by the prolongation. of the spark beyond the desired time of discharge of gap G1. If desired, the spark gap G1 in both Figs. 1 and 2 may be synchronized to spark after every charge from condenser C1 or after a certain number of charges from the condenser C1.

Figs. 3 and 4 show a plurality of variable condenser arrangements which maybe employed for the condenser Cl in either Fig. 1 or 2. In Fig. 3 the variable condenser arrangement comprises a plurality of condensers C2, C3 and C4, whose plates are connected inparallel relationship. In Fig. 4, the variable condenser arrangement constitutes three condensers C2, C3, C4, whose condenser plates are arranged in series relationship.

Fig. 5 shows 'a practical variable condenser which can be used for condenser C1 in either Fig. 1 or 2. This condenser is composed oi two spaced metallic plates l0 and II with teeth or vanes, and between these plates a. rotating dielectric disc l2 having toothed or serrated sections of alternating dielectric constants as shown.

In one embodiment actually constructed to prove the principles of the invention, the variable condenser C1 had a maximum capacity of about .005 mi. and a minimum capacity ofabout .0001 mi. with inch spaced plates. The potential of the source A was 600 volts and the voltage impressed on condenser C was about 5,000 or 6,000 volts.

What is claimed is: v

i. In a pulse generator system, a circuit for transforming direct current of low voltage to, direct current of higher voltage com 'ising a low voltage source of direct current, a variable capacitor in series with a rectifier connected across said source, and a series circuit of spark gap,

rectifier and an energy storage unit connected across said variable capacitor, means for contin-- ually varying the value of said variable capacitor,

said rectifiers being so poled that current can flow from said source through said first rectifier to said variable capacitor and current can iiow from said variable capacitor through said second rectifier to said storage unit, said spark gap having such spacing as to pass only voltages of.

values higher than the value of said source. said storage element comprising a network having a auaao multiplicity of sections of series inductance and shunt capacitance, and a load in series with another spark gap'connected to the output or said networ whereby the charging of said network to a .critical value appreciably higher than the value of said source causes a surge of current to flow through said load of a time duration determined in part at least by the constants of said network, and the spacing of said first spark gap prevents undesired prolongation of the discharge or said network.

2. In a voltage multiplier circuit. a source of elatively low voltage direct current, a variable 6 connected across said variable capacitor, said rectiflers being so poled that current flows through both said rectifiers in the same direction relative to said source, whereby a voltage of higher value is applied to said storage circuit by said variable capacitor than thatapplied to said capacitor by said source of low voltage direct current, said energy storage circuit comprising a network having a multiplicity of sec- GEORGE L. USSELMAN. 

